Simulation study on vertical transport of atrazine in soil column

A simulation experiment on vertical transport of herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) in soil column was conducted using lysimeter system. The atrazine concentrations in leaching water and soil samples in column at 8 layers with 10 cm thick of each layer were detected by high-performance liquid chromatography. The results show total atrazine amount in leaching water increases nonlinearly with the leaching time and the herbicide application rate, and the atrazine concentrations in column soil decrease with the vertical depth after water leaching. The distribution of atrazine mass in the system after 154 days were that among the applied atrazine, 0.3 ％ is out through leaching water, 1％ is methanol extractable residues in soil, 46 ％ is methanol nonextractable residues in soil, and 52 ％ is other loss (including volatilization and degradation). The study indicates movement of atrazine in agriculture soil may not only have relation to the properties of herbicide, but also to the herbicide application history.     

Can further mitigation of ammonia emissions reduce exceedances of particulate matter air quality standards?

Several studies point out the importance of agricultural emissions to particulate matter (PM) concentrations, and particularly of NH₃ emissions to PM_2.5. Our study used three different chemical transport models (CHIMERE, EMEP and LOTOS-EUROS) to quantify the reductions of PM_2.5 and PM₁₀ concentrations due to reductions of NH₃ emissions beyond the Gothenburg Protocol (GP), as well as due to the GP alone compared to 2009. Simulations of PM_2.5 and PM₁₀ concentrations using 2009 meteorology were undertaken for five emission scenarios: 2009 emissions (as the reference simulation), GP emissions in 2020, and further 10%, 20% and 30% NH₃ emission reductions in EU27 beyond the GP. The modelling results for the scenarios with further 10%, 20% and 30% NH₃ agriculture emission reductions in EU27 beyond the GP show that the reduction achieved in PM concentrations is not linear with the emission reductions. In fact, the results from the study show that the impact of ammonia emissions reduction is significantly more efficient when the emission reduction rises. Moreover, based on the evaluation on 2009, the modelling study shows that the expected impact of ammonia emissions on the formation of particulate ammonium was underestimated by all models. This would imply that the role of ammonia on PM concentration and exceedances of PM_2.5 and PM₁₀ limit values is likely to be even larger than quantified in this study. This study shows that the implementation of the emission reductions imposed by the revised GP for 2020 will not suffice to achieve compliance with PM limit values everywhere in Europe; hence further European and local measures may be considered. NH₃ emissions from agriculture can be further reduced with the implementation of proven and feasible measures (substitution of fertilizers, improved storage of manure, way fertilizer injections, etc., …), in order to reduce PM concentrations and their impacts on human health across Europe.     

Sand and dust storms: underrated natural hazards

Sand and dust storms (SDS) are wind erosion events typically associated with dryland regions, although they can occur in most environments and their impacts are frequently experienced outside drylands because desert dust haze often is transported great distances. SDS represent hazards to society in numerous ways, yet they do not feature prominently in the disasters literature. This paper considers SDS in a hazard context by examining their ramifications in economic, physical, and social terms, with a focus on agriculture, health, transport, utilities, households, and the commercial and manufacturing sector. There are few assessments of the economic consequences of SDS and those studies that have been conducted lack consistency in data collection methods and analysis. SDS do not result in the significant damage to infrastructure usually associated with many disasters, but the cumulative effects on society can be significant because SDS occur more commonly than most other types of natural hazard.     

基于垂直加密观测的北京地区霾和沙尘复合污染形成条件分析

为了弄清蒙古气旋外围出现的霾和沙尘复合污染特征及其形成的关键气象条件,本研究利用多种遥感设备（增强型云高仪、风廓线雷达和微波辐射计等）垂直加密观测数据,结合大气主要污染物（PM₁₀、PM_2.5、SO₂、NO₂）监测数据、加密自动气象站观测数据,以及常规地面和高空气象观测数据、NCEP再分析数据等,分析发生在北京春季的2次霾和沙尘重污染过程.结果表明,2017年5月4—5日为一次PM₁₀和PM_2.5混合污染过程,与上游地区强烈发展的蒙古气旋后部风沙区的输送有关.上游地区因受中-低空西来槽影响上升气流加强,使沙尘细颗粒物（粒径≤10 μm）悬浮于空中,由中-低空偏西风输送至下游地区,被北京及附近的弱下沉气流带至地面造成严重的PM₁₀、PM_2.5混合污染.其中,地面偏西风对上游地区的PM₁₀、PM_2.5的水平输送作用明显;2018年3月27—28日凌晨是受蒙古气旋底部低压区辐合作用和偏南气流输送作用形成的积累型霾（PM_2.5）污染.28日凌晨2：00开始蒙古气旋后部沙尘区随东-西向冷高压南压而向南扩散.随后冷高压不断东移形成回流偏东风,偏东风使北京及西北部地区的低层大气产生辐合上升运动,导致本地尘土扬起,造成PM_2.5重污染和PM₁₀极严重污染;浮尘天气引发的大气污染具有突发性特征,且持续时间较长.边界层高度低、低层大气存在逆温层（或等温层）并长时间维持是霾和沙尘复合污染形成和持续的重要条件.霾和沙尘复合重污染的形成是人为污染物、沙尘细颗粒物水平和垂直输送,以及大气层结稳定共同作用的结果.     

基于非线性破坏准则的边坡稳定性分析

Baker提出的非线性破坏准则是一种广义的岩土体强度准则,常规的M-C强度准则、格里菲斯强度准则以及Hoek-Brown强度准则均为其特例。该准则通过大量的三轴试验引入无量纲强度参数A,n和T,其中A为尺度参数用于控制剪切强度的大小;n为准则曲线的次数用于控制曲率;T为转换参数用于控制准则曲线与σ轴的位置,并反映其无量纲拉伸强度。以Baker非线性强度准则为基础,以极限分析上限法为工具,采用"切线法"思想研究了静、动荷载下边坡的稳定性,将边坡的稳定性问题转化为含多变量的数学优化问题,并给出其最优解。通过算例分析,研究了非线性强度参数对边坡稳定系数与屈服加速度系数的影响。结果表明:边坡稳定系数随无量纲参数A,T的增大而增大;边坡屈服加速度系数随坡高、坡角的增加而降低。     

典型地区饱和土壤中硝态氮垂直运移及拟合

采用室内土柱模拟的方法, 研究了封丘地区农田土壤中硝态氮垂直运移规律. 结果表明: 在饱和条件下, 不同浓度硝态氮溶液(100mg·L^-1、200mg·L^-1)处理的土壤, 硝态氮运移的穿透曲线间无明显影响. 用含有不同价态陪伴阳离子(K⁺和Ca²⁺)的硝态氮溶液处理黄潮土0～30cm土层和风沙土, 硝态氮运移的穿透曲线基本重合; 而陪伴Ca²⁺硝态氮溶液处理的黄潮土30～60cm、60～90cm土层中硝态氮出流时间具有滞后效应. 硝态氮溶液全部运移出土体所需时间越长, 穿透曲线越平缓、峰值越低. CXTFIT2.0数学模型估算的稳定水流条件下饱和土壤中硝态氮淋失量具有较高精度, 相关系数均达到极显著水平.     

稀土元素在土壤中迁移、转化模型的建立及验证

建立了稀土在褐土土壤中迁移、转化模型，定量评价稀土在土壤中的迁移、转化过程。模型包括土壤中稀土化学热力学平衡体系、土壤水分物理形状和土壤剖面的稀土通量。在中国农业大学内进行了田间实验，对模型进行了验证，模拟值与实测值能很好的拟合。     

Improving suitability of urban canals and canalized rivers for transportation,thermal energy extraction and recreation in two European delta cities

Canals and canalized rivers form a major part of surface water systems in European delta cities and societal ambitions to use these waters increase. This is the first assessment of how suitability of these waters can improve for three important uses: transportation, thermal energy extraction (TEE) and recreation. We assess suitability with Suitability Indices (SIs) and identify which alterations in the water system are needed to improve SI scores in Amsterdam, The Netherlands, and Ghent, Belgium. The results show spatial variability in suitability scores. Current suitability for transportation is low (SI score = 1) to excellent (SI score = 4), for TEE fair (SI score = 2) to excellent (SI score = 4), and suitability for recreation is low (SI score = 1). Suitability could improve by enlarging specific waterway dimensions, increasing discharge and clarity, and by enhancing microbiological water quality. The same methodology can be applied to optimize designs for new water bodies and for more water uses.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01759-3.     

唐山市PM2.5和O3的演变特征及其对大气复合污染的协同影响

通过采集唐山市2015~2021年7年间大气污染物PM_2.5、 O₃、 SO₂、 NO₂和CO浓度,以及气象要素温度（T）、相对湿度（RH）、风速等相关数据,结合相关性分析和后向轨迹聚类分析技术,分析研究了唐山市近7年间PM_2.5和O₃不同时段的变化特征,及其影响因素,探讨了气团传输对PM_2.5和O₃污染的贡献,揭示了PM_2.5和O₃对大气复合污染的协同影响机制.结果表明,唐山市2015~2021年间PM_2.5浓度呈逐年下降的趋势,而O₃浓度则呈现出单峰态变化趋势,峰值出现在2017年. PM_2.5和O₃浓度均呈现出明显的季节变化,其中PM_2.5表现为冬季最高夏季最低的特征,而O₃则表现为夏季最高而冬季最低的特征.此外,PM_2.5的日变化呈双峰态分布,峰值分别发生在工作日早高峰和晚高峰期间. O₃日变化则呈单峰态分布,峰值出现在下午紫外线照射较强时段. PM_2.5主要受SO₂、 NO₂和CO的正向影响,而O₃则主要受太阳辐射强度和温度的正向影响.在不同污染背景下,PM_2.5和O₃会受到来自不同方向气团传输的影响. PM_2.5和O₃对大气复合污染的协同作用在诸多因素的共同影响下,呈现出冬季明显的负向影响,而春、夏和秋季则明显的正向影响.在不同污染背景下,当PM_2.5浓度超过150 μg·m^-3时,PM_2.5和O₃的协同作用则表现为明显的负向作用.     

流域农业面源污染迁移过程与模型研究进展

当前农业面源污染仍是我国水污染的主要来源,面源污染过程涉及农业、水利、环境、生态等多学科交叉,是国内外环境污染学术研究和流域污染控制与管理关注的焦点之一。不同学科通常在不同的时空尺度上采用不同的方法研究农业面源污染的产生与迁移过程,如农业学科注重农田—山坡—流域尺度下灌溉、不同作物在不同阶段施肥、营养盐转化吸收及其土壤库收支与微生物对营养盐的作用等过程,但忽略了不同尺度或系统之间的迁移过程内在联系,尤其是较少开展集成模拟研究。本文综述了典型空间尺度（从田块到山坡,再到流域尺度）农业面源污染迁移过程及影响因素,总结了流域农业面源污染建模方法,提出在模型系统中除需要深入考虑田块、山坡等尺度的局部水文及其污染物产生、累积、释放与迁移外,还迫切需要综合考虑农田—山坡—流域系统的水文和污染物迁移过程与集成面源模型的研发。同时,针对农业面源污染迁移过程的尺度转换、建模方法和模型不确定性,分析了其现有研究存在的不足,并对未来研究进行了展望。